Gas jet pump



1965 H. J. SCHROEDER ETAL 3,

GAS JET PUMP Filed Dec. 13, 1963 s Sheets-Sheet 1 I INVENTORS HANS JOAC HIM SCHROEDER ERNST H. SAILER [ATTORNEYS Dec. 20, 1966 Filed Dec. 13, 1963 H. J. SCHROEDER ETAL GAS JET PUMP 5 Sheets-Sheet 2 INVENTORS HANS JOACHIM SCHROEDER ERNSTIl-SAILER ATTORNEYS Dec. 20, 1966 H.J.SCHROEDER ETAL 3,292,556

I GAS JET PUMP Filed Dec. 13, 1963 3 Sheets-Sheet 5 'INVENTORS HANS-JOACHIM SCHROEDER BY ERNST .SAILER ATTORNEYS United States Patent 9 3,292,556 GAS JET PUMP Hans Joachim Schroeder, Munich, and Ernst Heinrich Sailer, Garatshausen, Germany, assignors to BMW- Triebwerlrbau G.m.b.H., Munich-Allach, Germany Filed Dec. 13, 1963, Ser. No. 330,491 Claims priority, application Germany, Dec. 14, 1962, B 70,043 22 Claims. (Cl. 103-258) The present invention relates to a novel method of operating a jet pump or blower as well as to a novel pump or blower for delivering or for feeding and atomizing a powdered solid, liquid or gaseous material by means of a gaseous propellant stream which draws-in or sucks-in the material to be delivered or supplied out of a tank, container or vessel for such material and which discharges or exhausts the same from a mixture zone into a space with essentially the same or higher pressure than in the container for the material to be delivered or fed.

With such types of prior art gas jet pumps, aspirators or injectors, only a limited quantity of the material to be fed can actually be supplied or delivered with a continuous flow by utilization of the underpressure or vacuum at the suction aperture of the material to be supplied by reason of the given values of pressure and density of the propellant stream or propelling gas and of the material to be fed as well as by reason of the propelling gas quantity available per unit time and the given pressure in the mixing zone.

However, gas jet pumps operating in this manner, that is, in steady flow operation, require a disproportionately large quantity of propelling or driving gas per unit quantity of material to be fed so that the specific delivery and efficiency of such gas jet pumps is extremely limited.

Furthermore, known in the prior art is a jet blower in which the propelling gas stream is periodically interrupted by means of mechanically controlled elements, for example, by means of a rotary slide valve, whereby an intermittent supply or feed results therefrom with a slightly increased specific delivery. These prior art jet blowers, however, entail disadvantages since the control mechanism for the rotary slide valve requires considerable structural expenditures, and in practical operation, this control mechanism cannot adapt itself automatically to the pulsations or undulations inherent in the principle of operation and occurring in the supply lines for the propellant gas and the material to be fed so that also with these known jet blowers no considerable improvement of the feed output is attained.

The present invention is predicated on the aim to pro vide a jet pump or blower functioning intermittently during operation thereof exclusively by means involving only principles of flow technique and without any movable structural parts, and of which the specific delivery and efliciency is considerably higher than that .of the known jet pumps and jet blowers of the prior art. Inorder to attain this goal, the present invention proposes to so dimension the feed or supply means for the material to be fed that a critical mass ratio of propellant stream to feed material is exceeded periodically within the mixing zone, with which the velocity of the propellant stream changes over at the outlet or discharge from the Laval nozzle from supersonic to subsonic velocity so that a suction phase alternates periodically with an exhaust phase within the jet pump or blower.

According to the present invention the propellant stream thereby sucks-in or draws-in the material to be fed atan instantaneous mass ratio corresponding to the relationship G l+M l=2 2 E74: 2M1* whereby G is the mass of the propellant stream, G is the mass of the material to be delivered, M is the Mach number of the propellant stream, and u l, preferably a 2.

Measurements and tests with gas jet pumps which, according to the present invention, operate intermittently by relying exclusively on principles of flow technique, have shown that without additional constructive or structural expenditures, an increase of the ratio of quantity of fed material to quantity of propelling gas and therewith of the quantity of supplied or delivered material itself to a value several times that possible in the continuous operation with steady flow is achieved by the present invention. This is particularly of the greatest significance if, for reasons conditioned by the method of operation or for economic reasons, only a limited quantity of propellant is available, for example, if air or combustion gas is removed from a gas turbine for the atomization of the after burner fuel, of pest control means, of fire-extinguishing powder or the like.

Accordingly, it is an object of the present invention to provide a method for feeding materials by means of gas jet streams and a gas jet pump for use in connection with such method which obviate the aforementioned shortcomings and disadvantages encountered with the prior art methods and constructions.

Another object of the present invention resides in the provision of a gas jet system for the supply or feed of materials which permits an increase in the quantity of material to be fed with a given amount of propellant.

Still another object of the present invention resides in the provision of a gas jet pump for use in connection with the feed of materials which not only increases the ratio of materials delivered to the propellant quantities consumed but also permits an increase in the absolute value of the amount of the fed materials for a given system.

A still further object of the present invention resides in the provision of an automatically intermittently operable gas jet pump which obviates the need for complicated and expensive control mechanisms while, at the same time, assuring extreme reliability in operation owing to the fact that flow principles are used exclusively for the control of the intermittent operation thereof.

A further object of the present invention resides in the provision of a gas jet pump for feeding and delivering materials which can be readily adapted to existing conditions as regards propellant supply, nature of the material to be delivered, and feed thereof to and from the gas jet pump.

Still another object of the present invention resides in the provision of a gas jet pump system for feeding materials which permits a significant increase in the effective cross section of the suction apertures through which the fed material enters into the mixing path.

These and other objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, several embodiments in accordance with the present invention, and wherein:

FIGURES 1 to 8 are somewhat schematic partial crosssectional views of eight different embodiments of gas jet pumps in accordance with the present invention, and

FIGURE 9 is a diagram in which the mass ratio G /G of the propelled substance to propellant stream is plotted against the Mach number representing the flow velocity of the gas.

The present invention is characterized by a jet pump or blower which is so dimensioned that a critical mass ratio of propelled substance to propellant stream is periodically exceeded within the mixing zone of the jet pump ice so that the flow velocity of the propellant stream alternates periodically from supersonic to subsonic speed.

Referring now to the drawing wherein like reference numerals are used throughout the various views to designate like or functionally similar parts in the various views thereof, the basic construction of all of the embodiments of the present invention illustrated therein essentially consists of a nozzle 1 through which flows the propelling gas stream or jet, of the suction aperture or apertures 2 for the inlet or admission of the material to be fed and of a mixing zone 3 from which the mixture of fed material or propelled substance and propellant is exhausted or discharged. The supply of the material to be fed can be take place either by way of individual pipe lines or ducts distributed about the nozzle 1 or by an annular ductor ring-shaped line. Furthermore, a check valve of conventional construction may be installed into the supply line or lines for the material to be fed in order to prevent the return flow of the fed material from the mixture zone 3. Since such check valve may be of any conventional structure, a detailed showing thereof in the drawing has been dispensed with, except for a schematic showing in FIGS. 1 and 4.

In FIGURE '1, the nozzle 1 for the supply of the propellant is constructed as a Laval nozzle whereby the mixing zone 3 adjoins the nozzle, without enlargement in the diametric dimension thereof, in the axial extension of the nozzle outlet cross section whereas the material to be delivered flows from a check valve into the mixing zone by way of an annular line or duct 4.

In FIGURE 2, reference numeral 1a again designates a Laval nozzle for the propellant supply while reference numeral 2a designates the suction apertures and reference numeral 3a the mixing zone; however, the cross section of the mixing zone 3a is enlarged in this embodiment with respect to the outlet section of the nozzle 1a by a differential area or dimension 6.

FIGURE 3 again shows a Laval nozzle 1b as well as a mixing zone 3b enlarged by a diflerential area or dimension 7. The supply of the material to be fed takes place in the axial direction through an annular channel 8.

In FIGURES 4 and 5, each of the nozzles 1c and 1d for the supply of the propellant is constructed as a ring disk nozzle of essentially circular disk-like shape and defined by planes or slightly conically shaped walls 9 and 10. The mixing zones 30 and 3d, also of disk-like shape, adjoin the ring disk nozzles 1c and 1d. The propellant flows thereby axially through the channels 110 and 11d and is deflected radially Within the ring disk nozzles 1c and 1d; the material to be delivered or supplied also enters the mixing zones 30 and 3d axially through the circular ring-shaped suction apertures 2c and 2d and is exhausted or discharged in the radial direction out of the mixing zones 3c and 3d. Reference numeral 5d again designates in FIGURE 5 the diiferential area or dimension, by the amount of which the mixing zone 3d is enlarged compared to the disk cross section of the ring disk nozzle 1d thereof.

The mixing zones 3e and 3 in the embodiments of FIGURES 6 and 7 are provided downstream from the respective suction apertures 2e and 2 for the material to be fed, preferably at the downstream end thereof, with a slight cross-sectional reduction, for example, by about 5 to 10% with the formation of a re-entrant edge 12e or 12 In FIGURE 8 the nozzle 1g for the supply of the propellant is also constructed as ring disk nozzle, whereby the circular ring-shaped suction aperture 2g for the material to be fed or supplied adjoins directly a rounded-off portion 13 of the nozzle 1g and therewith forms a ring shaped edge 14 about which the stream lines of the gas jet flow expanding to supersonic velocities carry out a sweeping or deflecting motion (Prandtl-Meyer-Flow). By reason of the fact that the suction apertures 2g directly adjoin the edge 14, there is attained the advantage of smallest boundary layer formation up to the suction aper- OPERATION The operation of the gas jet pump according to the present invention is as follows:

The gas jet pump of the present invention, differing from the known systems, operates intermittently, that is, there is effectively formed a suction phase and an exhaust phase.

This mode of operation is achieved in that the supply line means for the substance to be propelled or material to be delivered are so dimensioned in a manner known to a person skilled in the art as regards the inlet aperture thereof into the mixing zone, the flow or conduction resistance, etc. that an instantaneous mass ratio of fed material or propelled substance to propellant stream G /G is established within the mixing zone which is larger than a critical mass ratio EL li 1 G 2M at which the Mach number M of the propellant stream at the discharge from the Laval nozzle changes over from supersonic velocity to subsonic velocity. According to the present invention the mass ratio within the mixing zone is to attain momentarily preferably more than two times (a) of the critical value.

During the suction phase, the propelling or driving jet flowing through the Laval nozzle expands to supersonic velocity. Accordingly, there prevails at the orifice of the nozzle into the mixing zone or at the end of the nozzle a pressure which is smaller than the pressure within the container or tank for the material to be delivered. The suction aperture for the material to be fed is located according to the present invention at the discharge of the Lavel nozzle into the mixing zone or into the dead space formed thereat in which prevails a vacuum or underpressure, and is matched thereto in such a manner that under the effect of the vacuum or underpressure prevailing within the dead space a large quantity of the material to be delivered is sucked into the mixing zone than the propellant stream is capable of continuously feeding or supplying into the external pressure prevailing at the end of the mixing zone by reason of the linear momentum" inherent in the jet at the end of the Laval nozzle. The flow of fed material is thus set into operation and leads to a clogging of the mixing channel in conjunction with a decrease in velocity of the propellant stream byv reason of the inertia of the material to be delivered.

A stoppage in the flow of material to be fed follows the clogging of the mixing channel. The propellant stream thereafter, i.e., when the above-defined critical mass ratio is a pressure higher than the atmospheric pressure. The fed material enclosed in the mixing zone as a result of the mass moment of the inertia is now exhausted or discharged by the propellant stream or jet due to the excess pressure thereof. During this exhaust phase, the supply of material to be fed to the mixing zone is interrupted. However, this supply is immediately started again as soori as the quantity of material delivered which has penetrated into the mixing zone has been exhausted or discharged and the flow in the Laval nozzle has again reverted to the supersonic condition (suction phase). The end pressure of the Laval nozzle has to be selected thereby so low that the jet, which fans out or bursts open according to the conditions of the Prandtl-Meyer corner flow from the Laval nozzle in case of absence of the fed material, still jumps over the suction aperture for the delivered material.

with its jet boundary in order to assure the regular sucking-in or drawing-in of new material to be fed as a result This basic principle of the operation according to the present invention of the gas jet pump finds application in all the embodiments described herein.

An improvement of the efiiciency and output of the gas jet pump illustrated in FIGURE 1 is achieved by the construction according to FIGURES 2 and 3,'as there is realized, by the sudden enlargement of the mixing path compared to the end cross section of the Laval nozzle by a difierential'area or dimension, an increase of the underpressure or vacuum and therewith an increase of the quantity ratio of fed material to propellant.

In FIGURES 4 and 5, the nozzle for the supply of propellant is constructed, in each case, as ring disk nozzle. The gas jet pump operates in the same manner as already described and is suited, for example, primarily for the uniform feeding or charging of axially symmetrical spaces with a liquid mist, for instance, as injection nozzle for an afterburner.

A projecting edge is provided in the embodiments of FIGURES 6 and 7 along each of the mixing paths downstream of the suction apertures for the material to be fed. This projecting edge has the purpose to fix, at this place, the compression shocks which occur during the suction phase in the mixing zone in order to prevent therewith that the pressure increase in the mixing zone starts already.

within the area of the suction apertures whereby no sufiicient vacuum or underpressure would be attained for the supply of the material to be fed and therewith the flow of delivered material would be interrupted.

While it is believed that a person skilled in the art will be able to carry out readily the present invention, given the aforementioned formula for the critical mass ratio, the following brief discussion is included to describe the applicable considerations to a typical example of operation.

The greatest mass of a gas G will fiow through a given flow cross section when the gas moves with the Lavalvelocity af c :a

where K c /c the relation of the specific heats of the gas; R =the gas constant of the gas;

g=the acceleration of gravity;

T =the temperature of the gas at rest.

It is assumed that this gas is loaded, in the mass ratio G /G for example with a substance G the specific gravity of which is 1000 times that of the gas and which is suspended in the gas in a finely divided pulverulent state so that it will always assume the velocity of the gas. It is further assumed that the volume occupied by the heavier substance is negligible, and that there does not take place any heat exchange between the pulverulent substance G and the gas G in the short time during which they flow together through the jet pump or blower. The gas-dynamic properties of the mixture G of pulverulent substance G and gas G will be those of a gas having the greater density of the mixture, respectively a smaller gas constant R inversely proportional to the ratio of the densities but otherwise having the same values K and T as the gas. Consequently, the mixture also has a Laval-velocity a and when the flow velocity c of the mixture becomes equal to its Laval-velocity n the mass G flowing through the cross section A =A will also reach its maximum.

The flow velocity of a gas is commonly expressed by a 6 non-dimensional quantity, the Mach number, which is esta-blished herein with the respective Laval-velocity a*.

Assuming the mass of the propellant stream to be constant, G =constant, M l=constant, the maximum quantity of mixture will flow through the mixing zone when M l.

Under this special or critical condition, one will obtain from the equations of steady flow through a mixing tube of the configuration shown in FIGURE 1 of the drawing and neglecting wall friction force, the relation which is plotted as a curve in the attached diagram of FIGURE 9.

As a specific example, employing the above principles, it may be assumed that in the jet pump or blower shown in FIGURE 1 of the drawing, the propellant stream enters the cylindrical mixing zone 3 with the Mach number M *=1.6, the value M *=1.6 being so chosen that a substantial negative pressure will be obtained for aspirating the propelled substance G The considerations which are to be applied in this respect are familiar to the person skilled in the art. The Mach number M for which a Laval nozzle is designed, results from its area ratio A /A in accordance with the relation .L. (Ki-1) where ALaval is the smallest cross sectional area of the Laval nozzle, and A is the cross-sectional area of the nozzle exit.

M *=l.6 for air corresponds to A /A =O.627. When the propellant stream in the present example enters the mixing zone with a Mach number M *:1.6, it can, in steady flow operation, propel a driven stream at the maximum mass ratio G /G :0.2375 (as shown by point a in the attached diagram). As soon as this mass ratio 62/61 is only slightly exceeded, the Mach number of the propellant stream will, in a normal compression shock, change abruptly from M *=1.6 (point a of FIGURE 9) to laval (point b of FIGURE 9).

The mass ratio is now to be increased in a substantial step to G /G =0.89 (point c of FIGURE 9). For the sake of simplicity, let it, for the time being, be assumed that the mass G is continuously forced into the mixing zone by a pump.

In order to cope with the mass ratio G /G =0.89 under steady flow conditions, the Mach number of the propellant stream must decrease suddenly from M *=1.6 to M "=0.431 (point d of FIGURE 9). This example has been so chosen that in the smallest cross section ALaval of the Laval nozzle, the Mach number M *=l will just be maintained. The propellant stream does no longer have supersonic velocity at any other point in the Laval nozzle. If the delivery of G is further increased, the point of operation of the jet pump or blower moves further upward from point d on the left-hand leg of the curve in the diagram. This can be carried to a point where the propellant stream will be completely chocked. If now the delivery suddenly ceases, the propellant stream with its full total pressure will drive through the mixing zone 3 the quantity of substance G which is contained therein, very much in the Way of a piston, and will finally expel this substance from the mixing zone.

However, the present invention relates to a self-aspirating jet pump or blower without a special supply pump for the substance G In that case, the propellant stream itself brings about a quick cyclical alternating sequence of aspiration and expulsion, by oscillating between supersonic velocity (M 1) and subsonic velocity (M l).

Experiments conducted with a jet pump according to the invention, the design Mach number of which was close to M 1.6, have shown that over a given period of time a mean mass ratio of propelled substance to propellant stream G :1 can be obtained. G designates the mass flow through the Laval nozzle at supersonic velocity. However, since during the expulsion phase the supply of substance G 'ceases, and the mass fiow of propellant G is temporarily reduced, the momentary mass ratio during the aspiration phase must have been at least G /G 2, and probably has been considerably higher. The mean mass ratio reaches a value which is 4.2 times that which could be expected from a jet pump calculated in accordance with the established methods of fluid dynamics, and operating with steady flow.

One of the measures, but only one of many which are familiar to a person skilled in the art, for increasing the supply of fluid to the mixing zone 3 is, for example, to increase progressively the outlet cross section of the supply conduit into the mixing zone, until the above described periodical operation occurs as may be readily determined empirically. A Laval nozzle and mixing zone of circular disk shape as shown in FIGURE 4 of the application drawings and its modifications, have been found to be of particular advantage in this respect. With such -a configuration it is possible to provide a plurality of openings 2 in the form of a crown or ring of holes of great total cross section, or a corresponding annular slot. The supply conduit must, of course, be of correspondingly large cross section in this case. Another possibility of bringing a maximum of fluid into the mixing zone is the appropriate selection of the Mach number M The criterium for a jet pump according to the invention is always a mass ratio G /G the mean value of which exceeds, preferably by more than double, the critical value indicated in the form of a curve in the diagram of FIG- URE 9. The fact that this condition is met will be recognizable by the periodic operation of the jet pump.

The propellant gas jet may be, for example, a combustion product or compressed air delivered by a compressor, for instance, air bled from the compressor of a gas turbine unit.

While we have shown and described several embodiments in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to a person skilled in the art; and we, therefore, do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

- We claim:

1. A gas jet pump for the delivery or for the feed and atomization of a pulverulent, liquid or gaseous substance by means of a gaseous propellant stream, comprising:

Laval nozzle means having nozzle outlet means forming an end cross section,

means forming a mixing zone disposed downstream of the nozzle means in the direction of flow of the propellant stream,

and supply line means for the substance to be delivered and terminating with suction aperture means thereof in said mixing zone downstream of the end cross section of said nozzle means,

the propellant stream leaving said nozzle means with supersonic velocities,

and said supply line means being so dimensioned that a critical mass ratio of propellant stream to substance to be delivered is periodically exceeded at which the velocity of the propellant stream at the outlet means 8 of said nozzle means changes from supersonic to subsonic velocity so that a suction phase periodically alternates with an exhaust phase within the jet pump, said Laval nozzle being constituted by an essentially circular disk-shaped space with the propellant stream flowing through said space radially from the inside toward the outside, and said aperture means being constructed of circular ring-shape.

2. A gas jet pump according to claim 1, wherein said spaced is defined by substantially plane walls.

3. A gas jet pump according to claim 1, wherein said space is defined by slightly comically shaped walls.

4. vA gas jet pump for the delivery or for the feed and atomization of a pulverulent, liquid-or gaseous substance, by means of a gaseous propellant stream, comprising:

nozzle means having nozzle outlet means forming an end cross section, means forming a mixing zone disposed downstream of the nozzle means in the direction of flow of the propellant stream,

and supply line means for the substance to be delivered and terminating with suction aperture means thereof in said mixing zone downstream of the end cross section of said nozzle means, the propellant stream leaving said nozzle means with supersonic velocities,

and said supply line means being so dimensioned that a critical mass ratio of propellant stream to substance to be delivered is periodically exceeded at which the velocity of the propellant stream at the outlet means of said nozzle means changes from supersonic to subsonic velocity so that a suction phase periodically alternates with an exhaust phase within the jet pump,

the propellant jet stream discharged at the end of the nozzle means fanning out under a predetermined 1 angle and the suction aperture means being arranged within the dead space defined by the jet boundary:

and terminating with suction aperture means thereof in said mixing zone downstream of the end cross" section of said nozzle means,

said nozzle means delivering the propellant stream with supersonic velocities, and said supply line means being so dimensioned that critical mass ratio of substance to be delivered to propellant stream is periodically exceeded at which the velocity of the propellant stream at the end cross section of said nozzle outlet means periodically changes from supersonic to subsonic velocity so that a suction phase periodically alternates with an ex haust phase within the jet pump,

said mixing zone being provided downstrea'm'of said aperture mean-s near the. downstream end thereof with a slight reduction in cross section by an amount.

of approximately 5 to 10%, thereby efiectively forming a re-entrant edge.

6. A gas jet pump for the delivery or for the feed and atomization of a pulverulent, liquid or gaseous substance by means of a gaseous propellant stream, comprising:

nozzle means having nozzle outlet means forming an end cross section,

means forming a mixing zone disposed downstream of the nozzle means in the direction of flow of the propellant stream, and supply line means for the substance to be delivered and terminating with suction aperture means thereof 9 in said mixing zone downstream of the end cross section of said nozzle means,

said nozzle means delivering the propellant stream with supersonic velocities,

and said supply line means being so dimensioned that a critical mass ratio of substance to be delivered to propellant stream is periodically exceeded at which the velocity of the propellant stream at the endcross section of said nozzle outlet means periodically changes from supersonic to subsonic velocity so that a suction phase periodically alternates with an exhaust phase within the jet pump,

said nozzle means being a ring disk nozzle for the supply of the propellant stream and said suction aperture means being constituted by a circular ringshaped aperture adjoining directly a rounded-01f portion of the ring disk nozzle with the formation of a ring-shaped edge.

7. A gas jet pump for the delivery or for the feed and 10 said Laval nozzle being constituted by an essentially circular disk-shaped space with the propellant stream flowing through said space radially from the inside toward the outside, and said aperture means being constructed of circular ring-shape. 9. A gas jet pump for the delivery or for the feed and atomization of a pulverulent, liquid or gaseous substance by means of a gaseous propellant stream, comprising:

and said supply line means being so dimensioned that a critical mass ratio of substance to be delivered to propellant stream is periodically exceeded at which atomization of a pulverulent, liquid or gaseous substance by means of a gaseous propellant stream, comprising:

nozzle means having nozzle outlet means forming an end cross section,

the velocity of the propellant stream at the end cross section of said nozzle outlet means periodically means forming a mixing zone disposed downstream of changes from supersonic to subsonic velocity so that the nozzle means in the direction of flow of the proa suction phase periodically alternates with an expellant stream, haust phase within the jet pump,

and supply line means for the substance to be delivered said supply line means and said nozzle means deliverand terminating with suction aperture means thereof ing, respectively, the substance to be delivered and in said mixing zone downstream of the end cross secthe propellant stream at an instantaneous mass ratio tion of said nozzle means, which corresponds to the formula said nozzle means delivering the propellant stream G2 2 w1th supersonrc veloc1t1es, al: 1]

and said supply line means being so dimensioned that 1 1 a critical mass ratio of substance to be delivered to Where 1 is the mass of the propellant Stream, 2 propellant stream is periodically exceed-ed at which the mass of the substance to be delivered, 1* the the velocity of the propellant stream at the end cross Mach number of the Propeliaht Stream and 5 section of said nozzle outlet means periodically the propellant j Stream discharged at the end of the changes from supersonic to subsonic velocity so Laval nozzle means fanning out under a predeterthat a suction phase periodically alternates with an milled ail'gie and the suction aperture means being exhaust phase within the jet pump, and line means including check valve means for conducting said material to said suction aperture means. 8. A gas jet pump for the delivery or for the feed and atomization of a pulverulent, liquid or gaseous substance by means of a gaseous propellant stream, comprising:

Laval nozzle means having nozzle outlet means forming an end cross section, means forming a mixing zone disposed downstream of arranged within the dead space defined by the jet boundary of the over-expanding jet. 10. A gas jet pump for the delivery or for the feed and atomization of a pulverulent, liquid or gaseous substance by means of a gaseous propellant stream, comprising:

Laval nozzle means having nozzle outlet means forming an end cross section,

means forming a mixing zone disposed downstream of the nozzle means in the direction of flow of the the nozzle means in the direction of flow of the propellant Stream,

propellant stream, and supply line means for the substance to be delivered and supply line means for the substance to be delivered and terminating With Suction aperture means theieof and terminating with suction aperture means thereof in said IhiXing Zone downstream f the end Cross in said mixing zone downstream of the end cross Section of Said IIOZZie means,

section of i nozzle means, said nozzle means delivering the propellant stream said nozzle means delivering the propellant stream with with supersonic Veiheities,

Supersonic l i i and said supply line means being so dimensioned that and i Supply i means b i so dimensioned that a critical mass ratio of substance to be delivered to a critical mass ratio of substance to be delivered to propellant Stream is Periodically exceeded at Which propellant tream is exceeded at the velocity Of the propellant stream at the end CI'OSS the velocity of the propellant stream at the end cross Section of Said nozzle Outlet means Periodically section f i nozzle Outlet means di l changes from supersonic to subsonic velocity so that changes from supersonic to subsonic velocity so that a Suction Phase Periodically alternates With an a suction phase periodically alternates with an exhaust Phase Within the l P p,

h t phase i hi h j pump, said supply line means and said nozzle means deliversaid supply line means and said nozzle means delivermg, respectively: the substance to he delivered and i respectively, the substance to be delivered and the propellant stream at an instantaneous mass ratio the propellant stream at an instantaneous mass ratio which corresponds to the formula which corresponds to the formula G2 1+M l 2 2 G1 2M1* where G is the mass of the propellant stream, G where G is the mass of the propellant stream, G the mass of the substance to be delivered, M the the mass of the substance to be delivered, M the Mach number of the propellant stream and 0452, Mach number of the propellant stream, and e22, said mixing zone being provided downstream of said aperture means near the downstream, end thereof with a slight reduction in cross section by an amount of approximately to thereby effectively forming a re-entrant edge.

11. A gas jet pump for the delivery or for the feed and atomization of a pulverulent, liquid or gaseous substance by means of a gaseous propellant stream, comprising:

Laval nozzle means having nozzle outlet means forming an end cross section,

means forming a mixing zone disposed downstream of the nozzle means in the direction of flow of the propellant stream,

and supply line means for the substance to be delivered and terminating with suction aperture means thereof in said mixing zone downstream of the end cross section of said nozzle means,

' said nozzle means delivering the propellant stream with supersonic velocities,

and said supply means being so dimensioned that a critical mass ratio of substance to be delivered to propellant stream is periodically exceeded at which the velocity of the propellant stream at the end cross section of said nozzle outlet means periodically changes from supersonic to subsonic velocity so that a suction phase periodically alternates with an exhaust phase Within the jet pump,

said supply line means and said nozzle means delivering, respectively, the substance to be delivered and the propellant stream at an instantaneous mass ratio which corresponds to the formula where G is the mass of the propellant stream, G the mass of the substance to be delivered, M the Mach number of the propellant stream and 1122,

said nozzle means being a ring disk nozzle for the supply of the propellant stream and said suction aperture means being constituted by a circular ring-shaped aperture adjoining directly a rounded-off portion of the ring disk nozzle with the formation of a ringshaped edge.

12. A gas jet pump for the delivery or for the feed and atomization of -a pulverulent, liquid or gaseous substance by means of a gaseous propellant stream, comprising:

Laval nozzle means having nozzle outlet means forming an end cross section,

means forming a mixing zone disposed downstream of the nozzle means in the direction of flow of the propellant stream,

and supply line means for the substance to be delivered and terminating with suction aperture means thereof in said mixing zone downstream of the end cross section of said nozzle means,

said nozzle means delivering the propellant stream with supersonic velocities,

and said supply line means being so dimensioned that a critical mass ratio of substance to be delivered to propellant stream is periodically exceeded at which the velocity of the propellant stream at the end cross section of said nozzle outlet means periodically changes from supersonic to subsonic velocity so that a suction phase periodically alternates with an exhaust phase within the jet pump,

said supply line means and said nozzle means delivering, respectively, the substance to be delivered and the propellant stream at an instantaneous mass ratio which corresponds to the formula where G is the mass of the propellant stream, G the mass of the substance to be delivered, Mfi the Mach number of the propellant stream and g2,

and line means including check valve means for-conducting said material to said suction aperture means. 13. A gas jet pump for the deliver or for the feed and atomization of a pulverulent, liquid or gaseous substance 5 by means of a gaseous propellant stream, comprising:

Laval nozzle means having nozzle outlet means forming an end cross section,

means forming a mixing zone disposed downstream of section of said nozzle outlet means periodically:

changes from supersonic to subsonic velocity so that a suction phase periodically alternates with an exhaust phase within the jet pump,

ing, respectively, the substance to be delivered and the propellant stream at an instantaneous mass ratio which corresponds to the formula where G is the mass of the propellant stream, G

the mass of the substance to be delivered, M the Mach number of the propellant stream and 0:22,

said nozzle means being a ring disk nozzle for the supply of fuel, and said suction aperture means being constituted by a circular ring-shaped aperture for said substance adjoining directly a rounded-off portion of the ring disk nozzle with the formation of a ring-shaped edge, and line means including check valve means for conducting said material to said suction aperture means. 14. A method for delivering or supplying and atomizing a pulverulent, liquid or gaseous pumped fluid substance by means of a gaseous propellant fluid stream, comprising the steps of:

expanding the high pressure propellant stream through a nozzle to a supersonic velocity of Mach M at the nozzle exit; introducing the supersonic propellant stream into a mixing chamber in the direction of the chamber outlet; increasing the pressure of the pumped fluid by introducing varying quantities of the pumped fluid into the mixing chamber for mixture with the propellant in proportions which cause the velocity of the propellant to vary from supersonic to subsonic, the mean mass ratio of pumped fluid to propellant fluid where a is greater than or equal to 2.

15. A gas jet pump for the delivery or for the feed and atomization of a pulverulent, liquid or gaseous pumped fluid substance by means of a gaseous propellant stream, comprising:

supersonic propellant fluid nozzle means having a nozzle outlet forming an end cross section, said nozzle means being operable to provide a propellant gas jet having a mean mass flow of G and a full expansion exit Mach number of M means forming a mixing chamber receiving the propellant gas jet and having an outlet conduit disposed said supply line means and said nozzle means deliver? downstream of the nozzle means in the direction of flow of the propellant jet;

supply line mean being operable to supply the pumped fluid and terminating with suction aperture means thereof in said mixing chamber downstream of the end cross section of said nozzle means, said supply line means also being operable to cause the instantaneous propellant flow within said nozzle means to periodically change from supersonic to subsonic with a corresponding periodic change in the instantaneous mass flow of the pumped fluid and a corresponding periodic change from a suction phase to an exhaust phase,

said supply means being correlated with the propellant fluid to satisfy the formula er i where on is greater than or equal to 2 and G is the mean mass flow of the pumped fluid.

16. The device of claim 15, wherein said mixing chamber has a cross section enlarged by a dilferential area compared to the end cross section of said nozzle means.

17. The device of claim 15, wherein said nozzle means is a Laval type nozzle.

18. The device of claim 15, wherein said nozzle means is a Laval type nozzle having an essentially circular discshaped space with the propellant stream flowing through said space radially from the inside toward the outside, and said suction aperture means ha a circular ring shape.

19. The device of claim 15, wherein said supply line means includes a check valve preventing reverse flow of the pumped fluid.

20. The device of claim 15, wherein said nozzle means is constructed so that the propellant jet streams discharged at the end of the nozzle means fans out under a predetermined angle, and the suction aperture means is located in the dead space defined by the jet boundary of the overexpanding jets.

21. The device of claim 15, wherein said mixing chamber is provided downstream of said aperture means with a slight reduction in cross section by an amount of approximately 5 to 10 percent, thereby effectively forming a re-entry edge.

22. A method of pumping a fluid susbtance by a propellant gas, comprising the steps of: delivering a propellant gas under pressure to a nozzle; moving the propellant through the nozzle and discharging the propellant at a supersonic speed; delivering the supersonic propellant to a mixing chamber for discharge out of an outlet to the chamber to create a suction, at the inlet to the mixing chamber, for the fluid substance; delivering the fluid substance to the mixing chamber, primarily in response to the suction, at a mass flow exceeding the mass flow that can be moved out of the outlet under steady state conditions by the propellant delivered at a speed exceeding the speed of sound, the delivering of the fluid generally choking the propellant to vary the speed of the delivered propellant between supersonic and subsonic velocity; and periodically delivering the subsonic propellant to the mixing chamber to substantially increase the pressure in the mixing chamber to subsequently exhaust the fluid substance out of the outlet to substantially clear the outlet.

References Cited by the Examiner UNITED STATES PATENTS 2,173,330 9/1939 Gregg 230- 2,248,073 7/1941 Gage 103-263 2,268,656 1/ 1942 Haltmeier 23095 2,532,554 12/1950 Jaecks 239-4 2,659,202 11/1953 Null 23095 3,009,826 11/1961 Straughn 239434 3,064,878 11/1962 Bayles et al. 230-92 3,188,009 6/1965 Miscovich 23092 OTHER REFERENCES Mechanical Engineering Thermodynamics by David A. Mooney, published by Prentice-Hall, 1953, pages 301 to 306.

MARK NEWMAN, Primary Examiner.

DONLEY I. STOCKING, Examiner.

W. L. FREEH, Assistant Examiner. 

1. A GAS JET PUMP FOR THE DELIVERY OR FOR THE FEED AND ATOMIZATION OF A PULVERULENT, LIQUID OR GASEOUS SUBSTANCE BY MEANS OF A GASEOUS PROPELLANT STREAM, COMPRISING: LAVAL NOZZLE MEANS HAVING NOZZLE OUTLET MEANS FORMING AN END CROSS SECTION, MEANS FORMING A MIXING ZONE DISPOSED DOWNSTREAM OF THE NOZZLE MEANS IN THE DIRECTION OF FLOW OF THE PROPELLANT STREAM, AND SUPPLY LINE MEANS FOR THE SUBSTANCE TO BE DELIVERED AND TERMINATING WITH SUCTION APERTURE MEANS THEREOF IN SAID MIXING ZONE DOWNSTREAM OF THE END CROSS SECTION OF SAID NOZZLE MEANS, THE PROPELLANT STREAM LEAVING SAID NOZZLE MEANS WITH SUPERSONIC VELOCITIES, AND SAID SUPPLY LINE MEANS BEING SO DIMENSIONED THAT A CRITICAL MASS RATIO OF PROPELLANT STREAM TO SUBSTANCE TO BE DELIVERED IS PERIODICALLY EXCEEDED AT WHICH THE VELOCITY OF THE PROPELLANT STREAM AT THE OUTLET MEANS OF SAID NOZZLE MEANS CHANGES FROM SUPERSONIC TO SUBSONIC VELOCITY SO THAT A SUCTION PHASE PERIODICALLY 